The high capacity I.C engines often have oil systems with two types of filters. One filter is put in series – all of the oil pumped from the oil pump runs through this filter. The second one is built into the system in parallel and about 10% of oil flows through it. This oil, after being purified, goes back to the oil sump. The full flow filter, being part of such a system, is a filter of medium purifying capabilities while the by-pass filter is the fine medium here. In the oil system, centrifugal filters are often applied as by-pass filters, where contaminants are separated from the oil using the centrifugal forces. Filters with a medium made out of special fabrics or filtering papers are also used. The characteristic feature of by-pass filters with a partition is, that during the exploitation the amount of oil being filtered is reducing. This happens as a result of flow resistance increasing while the filtration partition is getting blocked. In some engines with functioning series-by-pass oil system there is a tendency to use can filters with two filtration cartridges – full flow and by-pass. Such combined filters occupy less space and the replacement is much shorter. In such a filter dividing the oil flow into the main one, directed further to the engine, and the by-pass one, which after being properly purified flows back into the oil sump.
Spin-on oil filter with the full-flow and by-pass cartridge